ce188d4d |
1 | /* libFLAC - Free Lossless Audio Codec library |
2 | * Copyright (C) 2001-2009 Josh Coalson |
3 | * Copyright (C) 2011-2016 Xiph.Org Foundation |
4 | * |
5 | * Redistribution and use in source and binary forms, with or without |
6 | * modification, are permitted provided that the following conditions |
7 | * are met: |
8 | * |
9 | * - Redistributions of source code must retain the above copyright |
10 | * notice, this list of conditions and the following disclaimer. |
11 | * |
12 | * - Redistributions in binary form must reproduce the above copyright |
13 | * notice, this list of conditions and the following disclaimer in the |
14 | * documentation and/or other materials provided with the distribution. |
15 | * |
16 | * - Neither the name of the Xiph.org Foundation nor the names of its |
17 | * contributors may be used to endorse or promote products derived from |
18 | * this software without specific prior written permission. |
19 | * |
20 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
21 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
22 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
23 | * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR |
24 | * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
25 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
26 | * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
27 | * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
28 | * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
29 | * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
30 | * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
31 | */ |
32 | |
33 | #ifndef FLAC__PRIVATE__BITMATH_H |
34 | #define FLAC__PRIVATE__BITMATH_H |
35 | |
36 | #include "FLAC/ordinals.h" |
37 | #include "FLAC/assert.h" |
38 | |
39 | #include "share/compat.h" |
40 | |
41 | #if defined(_MSC_VER) |
42 | #include <intrin.h> /* for _BitScanReverse* */ |
43 | #endif |
44 | |
45 | /* Will never be emitted for MSVC, GCC, Intel compilers */ |
46 | static inline unsigned int FLAC__clz_soft_uint32(FLAC__uint32 word) |
47 | { |
48 | static const unsigned char byte_to_unary_table[] = { |
49 | 8, 7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4, |
50 | 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, |
51 | 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, |
52 | 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, |
53 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, |
54 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, |
55 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, |
56 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, |
57 | 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
58 | 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
59 | 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
60 | 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
61 | 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
62 | 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
63 | 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
64 | 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
65 | }; |
66 | |
67 | return word > 0xffffff ? byte_to_unary_table[word >> 24] : |
68 | word > 0xffff ? byte_to_unary_table[word >> 16] + 8 : |
69 | word > 0xff ? byte_to_unary_table[word >> 8] + 16 : |
70 | byte_to_unary_table[word] + 24; |
71 | } |
72 | |
73 | static inline unsigned int FLAC__clz_uint32(FLAC__uint32 v) |
74 | { |
75 | /* Never used with input 0 */ |
76 | FLAC__ASSERT(v > 0); |
77 | #if defined(__INTEL_COMPILER) |
78 | return _bit_scan_reverse(v) ^ 31U; |
79 | #elif defined(__GNUC__) && (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)) |
80 | /* This will translate either to (bsr ^ 31U), clz , ctlz, cntlz, lzcnt depending on |
81 | * -march= setting or to a software routine in exotic machines. */ |
82 | return __builtin_clz(v); |
83 | #elif defined(_MSC_VER) |
84 | { |
85 | unsigned long idx; |
86 | _BitScanReverse(&idx, v); |
87 | return idx ^ 31U; |
88 | } |
89 | #else |
90 | return FLAC__clz_soft_uint32(v); |
91 | #endif |
92 | } |
93 | |
94 | /* Used when 64-bit bsr/clz is unavailable; can use 32-bit bsr/clz when possible */ |
95 | static inline unsigned int FLAC__clz_soft_uint64(FLAC__uint64 word) |
96 | { |
97 | return (FLAC__uint32)(word>>32) ? FLAC__clz_uint32((FLAC__uint32)(word>>32)) : |
98 | FLAC__clz_uint32((FLAC__uint32)word) + 32; |
99 | } |
100 | |
101 | static inline unsigned int FLAC__clz_uint64(FLAC__uint64 v) |
102 | { |
103 | /* Never used with input 0 */ |
104 | FLAC__ASSERT(v > 0); |
105 | #if defined(__GNUC__) && (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)) |
106 | return __builtin_clzll(v); |
107 | #elif (defined(__INTEL_COMPILER) || defined(_MSC_VER)) && (defined(_M_IA64) || defined(_M_X64)) |
108 | { |
109 | unsigned long idx; |
110 | _BitScanReverse64(&idx, v); |
111 | return idx ^ 63U; |
112 | } |
113 | #else |
114 | return FLAC__clz_soft_uint64(v); |
115 | #endif |
116 | } |
117 | |
118 | /* These two functions work with input 0 */ |
119 | static inline unsigned int FLAC__clz2_uint32(FLAC__uint32 v) |
120 | { |
121 | if (!v) |
122 | return 32; |
123 | return FLAC__clz_uint32(v); |
124 | } |
125 | |
126 | static inline unsigned int FLAC__clz2_uint64(FLAC__uint64 v) |
127 | { |
128 | if (!v) |
129 | return 64; |
130 | return FLAC__clz_uint64(v); |
131 | } |
132 | |
133 | /* An example of what FLAC__bitmath_ilog2() computes: |
134 | * |
135 | * ilog2( 0) = assertion failure |
136 | * ilog2( 1) = 0 |
137 | * ilog2( 2) = 1 |
138 | * ilog2( 3) = 1 |
139 | * ilog2( 4) = 2 |
140 | * ilog2( 5) = 2 |
141 | * ilog2( 6) = 2 |
142 | * ilog2( 7) = 2 |
143 | * ilog2( 8) = 3 |
144 | * ilog2( 9) = 3 |
145 | * ilog2(10) = 3 |
146 | * ilog2(11) = 3 |
147 | * ilog2(12) = 3 |
148 | * ilog2(13) = 3 |
149 | * ilog2(14) = 3 |
150 | * ilog2(15) = 3 |
151 | * ilog2(16) = 4 |
152 | * ilog2(17) = 4 |
153 | * ilog2(18) = 4 |
154 | */ |
155 | |
156 | static inline unsigned FLAC__bitmath_ilog2(FLAC__uint32 v) |
157 | { |
158 | FLAC__ASSERT(v > 0); |
159 | #if defined(__INTEL_COMPILER) |
160 | return _bit_scan_reverse(v); |
161 | #elif defined(_MSC_VER) |
162 | { |
163 | unsigned long idx; |
164 | _BitScanReverse(&idx, v); |
165 | return idx; |
166 | } |
167 | #else |
168 | return FLAC__clz_uint32(v) ^ 31U; |
169 | #endif |
170 | } |
171 | |
172 | static inline unsigned FLAC__bitmath_ilog2_wide(FLAC__uint64 v) |
173 | { |
174 | FLAC__ASSERT(v > 0); |
175 | #if defined(__GNUC__) && (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)) |
176 | return __builtin_clzll(v) ^ 63U; |
177 | /* Sorry, only supported in x64/Itanium.. and both have fast FPU which makes integer-only encoder pointless */ |
178 | #elif (defined(__INTEL_COMPILER) || defined(_MSC_VER)) && (defined(_M_IA64) || defined(_M_X64)) |
179 | { |
180 | unsigned long idx; |
181 | _BitScanReverse64(&idx, v); |
182 | return idx; |
183 | } |
184 | #else |
185 | /* Brain-damaged compilers will use the fastest possible way that is, |
186 | de Bruijn sequences (http://supertech.csail.mit.edu/papers/debruijn.pdf) |
187 | (C) Timothy B. Terriberry (tterribe@xiph.org) 2001-2009 CC0 (Public domain). |
188 | */ |
189 | { |
190 | static const unsigned char DEBRUIJN_IDX64[64]={ |
191 | 0, 1, 2, 7, 3,13, 8,19, 4,25,14,28, 9,34,20,40, |
192 | 5,17,26,38,15,46,29,48,10,31,35,54,21,50,41,57, |
193 | 63, 6,12,18,24,27,33,39,16,37,45,47,30,53,49,56, |
194 | 62,11,23,32,36,44,52,55,61,22,43,51,60,42,59,58 |
195 | }; |
196 | v|= v>>1; |
197 | v|= v>>2; |
198 | v|= v>>4; |
199 | v|= v>>8; |
200 | v|= v>>16; |
201 | v|= v>>32; |
202 | v= (v>>1)+1; |
203 | return DEBRUIJN_IDX64[v*FLAC__U64L(0x218A392CD3D5DBF)>>58&0x3F]; |
204 | } |
205 | #endif |
206 | } |
207 | |
208 | unsigned FLAC__bitmath_silog2(FLAC__int64 v); |
209 | |
210 | #endif |